>At 05:52 PM 7/18/01 -0500, Aaron Swartz wrote:
>>>The essence of this issue seems to involve the idea that the
>>>act of naming something in the internet is somehow, special.
>>>That if a processor is told that something has URI ISBN-12345
>>>or whatever, it had better not match that with anything that
>>>it does not 'know' is named ISBN-12345. On the other hand,
>>>if a node is not named, then it can be matched with anything
>>>that matches its properties.
>>
>>Pat Hayes has said repeatedly that one can pretty much only infer
>>from an existential the same things they could from a specific
>>identifier. Obviously, he has studied this more than I have, but it
>>seems to me that people are asking anonymous nodes to mean more
>>than they really do.
>
>I agree with your last statement (for some value of "really do
>mean", since that's for us collectively to define).
>
>I think the other part of Pat's position here is that when the
>variable is used in the query role (i.e. "does something satisfying
><foo> exist?" or "Looking for something that satisfies <foo>"), it
>is NOT being used as an existential but (in some sense) as a
>universally quantified value.
Right, though that "(in some sense)" deserves to be made more
explicit, which I will try to do before the f2f meeting. I mean, it
is an existential, strictly speaking, but queries are functionally
similar to *negated* assertions, so the machinery you need to handle
an existential in a query is the same as what you need to handle a
universal in an assertion. This is one of those things that just kind
of gets to be part of the atmosphere to anyone working in logic. In
most inference engines you can't tell asserted existentials from
queried universals, and vice versa.
Pat
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